I have project where I need to log temperature around 600 Celsius degrees in few spots and control 220v "oven". I'm looking forward to use arduino and K type thermocouple probe's like this: http://www.ebay.com/itm/180937152179As I understand for arduino I also need thermocouple amplifier probably like this: https://www.adafruit.com/products/269 (digital quite expensive 17.5$ per peace)

Questions:1. Is there cheaper/alternative way to go? I need 6 - 8 spots to log so it's go around 150$ for thermometers 2. There is IC AD595 10$ per peace (analog). Still ~ 100$. For this IC do I really need ice point reference?3. What would be cheapest "industrial" solution for logging stuff up to 1000C degrees?

May be You have some experiences with these or similar products and can share about reliability & accuracy & "What to do or not to do"...

You could use relays to switch each thermocouple in turn to one thermocouple amplifier. This will introduce cold-end error due to the metal missmatch at the thermocouple connections. You can either choose to ignore the error (20degC or so) or it can be compensated for by having and RTD measure ambient temperature, which is then subtracted from the measured temperature.

You could use relays to switch each thermocouple in turn to one thermocouple amplifier. This will introduce cold-end error due to the metal missmatch at the thermocouple connections. You can either choose to ignore the error (20degC or so) or it can be compensated for by having and RTD measure ambient temperature, which is then subtracted from the measured temperature.

If you place the relays close to the thermocouple interface IC the ambient temperature at that point should be the same and so the compensation performed by the TC interface chip should still be valid. Only if the relays are placed externally and are at different ambient temperature then the TC interface chip is at would there be a compensation problem.

FYI, MAX6675 has been replaced by MAX31855, which has wider temperature sensing range, better resolution, and is available in versions for several different thermocouple types. Still has an SPI interface, but the data format is changed from the MAX6675, so libraries for the earlier part will not work for the MAX31855.

FYI, MAX6675 has been replaced by MAX31855, which has wider temperature sensing range, better resolution, and is available in versions for several different thermocouple types. Still has an SPI interface, but the data format is changed from the MAX6675, so libraries for the earlier part will not work for the MAX31855.

LeXLuther422

You can also get a couple as a Sample from Maxim when I did it I got 3 of them for free. https://shop.maximintegrated.com/storefront/searchsample.do?event=Sample&menuitem=Sample&Partnumber=MAX31855KASA%2B

You can also get a couple as a Sample from Maxim when I did it I got 3 of them for free. https://shop.maximintegrated.com/storefront/searchsample.do?event=Sample&menuitem=Sample&Partnumber=MAX31855KASA%2B